The Sliding Corollary
by Daedaleopsis
Summary: Penny and Sheldon get pulled into an alternate dimension by mistake. Will they ever find their way back home?
1. Chapter 1

A/N: Okay, show of hands, who remembers the 90's sci-fi show Sliders? It had such a great premise, but had lots of problems. It was canceled, picked up by another network, and along the way, lost all but one of the original cast. It still deserves some love, though, and if you're interested, it looks like it just became available on Netflix. I ignored/changed some of the later canon of Sliders, but I hope you like my story anyway!

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The bus trip should have been the first thing that tipped her off. It was a weird thing to be running through her mind as Penny tried to fend off the attack of the ten-foot bird (which resembled a blue ostrich with sharp teeth) with nothing more than a pointed stick, but that's what she was thinking. She managed to jab her improvised spear up into the bird's open mouth. It screamed and shook its head, spraying blood everywhere, and then retreated with a loud shriek.

"How much longer, Sheldon?" Penny cried, panting.

"Fourteen minutes, twenty-eight seconds," he called back, checking the bulky device in his hand.

"Think we can avoid those monster birds for another fifteen minutes?" she asked dubiously.

He pointed upwards into the leafy canopy that stretched above their heads. "I think we'll have to climb," he said.

Penny made a face to show what she thought of that idea. "What if there's also monster spiders and monster snakes?"

He shook his head. "We'll have to risk it."

As Penny pulled herself upward, scraping elbows and palms on the rough tree bark, she wondered for the thousandth time if this all could have been avoided somehow. If only the contents of that dusty cardboard box had turned out to be a time-traveling machine instead of that stupid alternate-reality-portal thingy. She should have known something strange was going on when Sheldon was willing to take three buses, braving exposure to all sorts of public germs, to get to an estate sale. The deceased was one Amanda Mallory, mother to the late Quinn Mallory, a once-promising physics student with unconventional ideas. Quinn had gone missing over twenty years ago, and there were many rumors about his disappearance. One of them said that Mallory had managed to invent a time-traveling device. Sheldon, an avid _Doctor Who_ fan with far too much disposable income, had gone to the estate sale and, for a little over fifty bucks, had purchased an old box full of assorted electronic parts. He had explained all this to Penny as he was unpacking the contents of the box. She commented wryly that she was sure he had overpaid for it, whatever the price, since all the technology was bound to be obsolete—except her term was "worthless crap".

Sheldon had immediately started tinkering with some of the devices he purchased, but it was weeks before he got one of them repaired. He stared in astonishment at the whirling, funnel-shaped vortex hovering in the air in front of him. It worked! He was so excited, he couldn't wait to tell someone. Leonard had gone out to a movie with Raj and Howard, but he was sure they would want to see this right away. He picked up his cell phone and speed-dialed Leonard. It went straight to voicemail. Sheldon groaned in frustration. _What a wretched time for Leonard's phone to be off_ , he thought irritably. He tried calling Raj with the same result. Howard was only a valued acquaintance, but Sheldon would seriously consider upgrading his status to that of friend if only his phone was on. He never got the chance to find out. He heard the door open, and Penny called out, "Hey Sheldon, how come you're late for laundry... Holy crap on a cracker, what is that thing?"

"I believe it is a time traveling portal," Sheldon said. His voice was unsteady, but he looked at that mysterious vortex worshipfully, like it was the answer to life, the universe and everything.

She dropped her laundry basket on the floor with a thud. "Uh... is that a joke? Does it actually work?"

"I haven't gotten to the experimental testing phase yet. I just generated this portal a few minutes ago," Sheldon replied, picking up the device and pressing a few buttons.

"Wow, this is frickin' awesome," Penny enthused, lifting a finger to poke at the strange phenomenon.

"Don't touch that!" cried Sheldon, but it was too late. Before his horrified eyes, her figure seemed to stretch and elongate as she was pulled inexorably into the vortex. _Penny!_ He only had a split second to act. Clutching the remote tightly in one hand, he grabbed her wrist with his other hand. The portal yawned open like a hungry maw and devoured both of them before shrinking down into nothingness.

They had been traveling together ever since. It didn't take Sheldon long to deduce that the device allowed them to visit alternate dimensions instead of traveling through time. He had been disappointed for only a moment before getting caught up in the excitement of the possibilities of this new technology. Penny just wanted him to figure out the device so they could get back to Pasadena... _their_ Pasadena. Apparently, the device with which Sheldon had been experimenting was a crude prototype. It had never been configured to store the information needed to return them to their own reality, so they roamed through parallel dimensions trying to find their way back home.

In the past eight months, they had visited dozens of different Earths. Every time, they landed in the same geographic location, but in a parallel universe. Each world was unique. Some worlds were not that different from theirs. Most of the other ones were downright scary. In one alternate world, California was a prison state where political prisoners were exiled. In another one, they had been chased by strange mutated creatures that looked like large insects. Once, they had landed in the middle of a swift-flowing river and almost drowned.

Penny couldn't wait to leave this world, a primeval nightmare dominated by giant birds with razor-sharp teeth and yard-long poisonous scorpions. She reached down to help Sheldon up to a wide branch, and he accepted her help without comment. They had both changed a lot in the last several months. For one thing, they had become much more dependent on each other, learning to respect each other's strengths and rely on their instincts to keep them alive. Touching was another thing that Sheldon had simply had to get used to. Penny held his hand tightly whenever they had to jump through a portal and clung to him when she was scared. He tried not to admit to himself that sometimes he drew comfort from her touch as well.

Before the accident that had stranded them far from home, Sheldon had reluctantly starting dating Amy, a female scientist. He had liked her enough to make changes to his schedule to include date nights, but he still cringed when she insisted on holding his hand. All he really wanted was for them to continue to spend time together, but she had constantly been pressuring him for a more physical relationship. He hadn't been ready for it, and wasn't sure he ever would be, at least with her.

He glanced over at Penny. She rarely mentioned Leonard either. They both knew that by now, even if they could get back home, there was a good chance he had moved on and was dating someone new. Penny had once confided that she had agreed to get back together with Leonard in a moment of weakness. She had been feeling lonely and disillusioned about her lack of progress with her acting career. Leonard's fawning attention had been the sop to her ego that she needed, even though she knew she wasn't any more in love with him than she was the first time around. She'd tried to do the right thing and let him go when it was clear he cared for her much more than she cared for him. But when her self-esteem hit an all-time low, she had agreed to a "beta test" with Leonard. Sheldon had asked her not to hurt his friend, but there was no way she could have done what he wanted. Her relationship with Leonard had been too deeply flawed and unbalanced.

Looking over at Penny, Sheldon wondered if she had been relieved as he was to find some way out of their dating dilemmas. His thoughts were interrupted by a beeping from the bulky device in his hand. He looked up to see Penny crouched on a nearby branch, guarding his back and still holding the improvised spear. He felt a sense of calm come over him, knowing that she was looking out for him. He hadn't chosen her as a traveling companion, but in retrospect, he couldn't have picked a better one.

"It's time," he murmured, pressing the buttons that would activate the portal. Penny nodded and tightened the straps on her backpack. The supplies they carried had saved their lives numerous occasions. Sheldon pointed the hand-held remote at the air beneath their feet. Penny reached over and interlaced her fingers with his as they took a deep breath and jumped into the whirling vortex.


	2. Chapter 2

Penny and Sheldon hid shivering behind the concrete pylon of an overpass. Sheldon could vividly feel the tremors that shook her body, since she was pressed tightly against his thin but solid frame.

"Think we can just hide til our next leap?" she asked.

He consulted the boxy, handheld device. "Hide for three days, seventeen hours and four minutes? Unlikely."

She shuddered. "I know we've seen worse—wars, an ice age, floods—but this Earth really creeps the hell out of me."

Hiding had become their "standard protocol", as Sheldon liked to put it, their first and best reaction to an unknown environment and culture. They had once made the mistake of relaxing in a Pasadena that seemed very similar to their own... until they had seen one man spit something like venom into the face of another man he had been arguing with. The second man had died in seconds, screaming the whole time. Since then, Sheldon had no problem convincing Penny to be cautious.

"Why are they all dressed like they're in some bad porno?" Penny asked, shock and distaste coloring her voice.

She was right. The women wore sheer outfits made of gauze or netting, leaving nothing to the imagination. Almost all the men wore black, in either skin-tight shorts, skin-tight briefs, or thongs. Their torsos were left bare, but they all wore a metallic collar around their necks.

Sheldon squirmed uncomfortably at all the nudity on display. After a moment, he mused, "I wonder why only the men wear those collars?"

"I don't think it's because they get special privileges," Penny whispered, her warm breath fanning his ear as she leaned closer. "Look. The men are all following the women."

Sheldon was annoyed that he hadn't noticed it first, the subservient way the men stayed just a step or two behind whatever woman with whom they seemed to be associated. Then again, it was very distracting to have Penny pressed up against him like she was. Being in almost constant danger made her a tad... clingy. Not that she was afraid; she was more capable of defending herself than he was. She just seemed to derive emotional comfort from close physical proximity to him. He told himself it was only for her benefit that he wrapped an arm around her shoulders and pulled her closer. He could feel her shiver, and knew her well enough by now to understand that she was uneasy but not fearful.

"So what do you want to do? Should we just wander around fully dressed and pretend we're not from around here? We could try to strip down to our skivvies, but I'm not sure we'd blend in any better, especially if you still wear those stupid tighty-whitey briefs," Penny said, punctuating that last statement with a roll of her eyes.

"There is absolutely nothing wrong with my choice of undergarments," Sheldon replied haughtily, then added in a more reasonable tone, "However, I concur. Neither our clothing nor our unmentionables would allow us to assimilate successfully, so we may as well remain as we are."

When they came to a civilized world, their first goal was often to appropriate some funds. Over the past few months, Sheldon had tweaked his considerable computer skills to become a decent hacker. He could usually create passable fake ID's for them and siphon a small amount of money into an account without anyone the wiser. They only ever took enough to buy necessities and pay for a place to stay until their next jump. They would also restock their packs with food, water and other essentials. Penny thought of the giant blue birds and wondered if they could somehow fit a harpoon or maybe a machine gun into a backpack.

"Looks like we're in a commercial part of town... there's lots of shops," Penny said. "Maybe we can find a library or some other place with free internet access. I think we need to get moving though, before it gets too late in the day. I don't think this is the kind of place we want to be hanging around after it gets dark."

"Agreed," Sheldon said. He peered warily around the corner of the pylon. No one was nearby, so he grabbed Penny's hand and tugged her forward. As they began to walk down the nearest street, their appearance was immediately noticed. Women began to congregate in small groups, whispering to each other, while the men shot them awed or hostile glances.

"I've got a bad feeling about this," Penny quipped sardonically to Sheldon. They were almost across from the first retail shop on the street, a clothing store, and Penny pulled on Sheldon's hand. Wordlessly, he trailed along behind her. As they entered the building, a small bell at the top of the door tinkled merrily. A middle-aged woman with dark hair was standing behind the counter. At the sound of the bell, she looked up, and then her jaw dropped as she saw the two of them.

"Land's sakes, what on earth are you wearin'? Did you two just get off the plane from Russia or somethin'?" the woman drawled, her southern dialect making her words sound lazy even though she looked rather shocked.

Penny flicked a glance at Sheldon, telling him with her eyes to let her handle this. He nodded almost imperceptibly.

" _Da_ , you very good guesser!" Penny exclaimed in an atrocious Russian accent. "Ve just arrive from Moscow. California ees very different from ze motherland."

Sheldon was desperately hoping the shopkeeper didn't know what a real Russian accent sounded like, because to his ears, Penny sounded a lot more French than Russian.

"Why, bless your heart, dearie, that was just a figure of speech! Don't tell me that Russia's gone off the Pact," the woman said with a sharp look at Sheldon.

" _Nyet_ , of course not," Penny replied nervously, watching the brunette's face carefully.

The woman pressed her maroon-tinted lips together and fluffed her hair. "I should think not," she drawled with a laugh. "That would be ridiculous. The only real hold-outs are deep in the wilds of Africa and South America, and dearie, _no one_ wants to go there."

She came around the counter, her dark brown hair swinging to the side to reveal small breasts clearly visible through a sheer black negligee. Penny was still holding Sheldon's hand, and she dug her nails into his palm to remind him not to react. He tensed, but it was hard to tell whether that was in response to the woman's outfit or the sharp pain caused by Penny's nails.

"My name's Marci," she said, extending a hand to Penny. "Now why don't y'all come with me and we'll see about finding you some real clothes. Oh, and your man too," she said with a quick dismissive glance at Sheldon.

"Um, sure... I mean, _da._ Sheldon, why don't you look around while I try on some things?" Penny said, remembering her accent just in time.

Marci looked startled. "Don't tell me you call him by name, sugar. You must be _very_ attached to this one." She sashayed back toward Sheldon and circled him, looking him up and down. With a swift movement, she snagged the neckline of his double-layered tees and pulled them down a few inches. Then she recoiled in shock.

"He's not collared!" Marci shrieked. She backed up toward the counter, then snatched up what looked like a cell phone.

Penny grabbed it out of the woman's hand. "Wait, please! Ve were... ve were robbed right after we left ze airport. They took our good clothes, everything. They even stole...um... my man's collar."

The clerk eyed Penny suspiciously. "You were robbed? Why on earth would anyone in their right minds steal a collar? Lord knows what liberated men are capable of."

"It vas... ze latest model, brand new," Penny improvised. "Much better than vat you have in California."

Marci favored Penny with another hard look, but then her face softened. "Well, bless your heart, you poor things! I think I have an old collar of Kurt's lying around that you can put on your man 'til you get things straightened out." She turned her head toward the back of the store and hollered, "Boy! Come on out here!"

Penny exchanged startled glances with Sheldon at that. The more Penny learned about this culture, the less she liked it. Putting one of those collars on Sheldon seemed like a bad idea, but from the way Marci reacted to his bare neck, it might be unavoidable. _Just so long as the collars don't explode like in that stupid sci-fi movie Sheldon once made me watch_ , Penny thought.

There was a rustling from the back of the shop, and a black curtain was pushed aside by a huge man who rippled with muscle. As he raised his head and rumbled "Mistress" in answer to Marci's shout, Penny gasped in shock. It was Kurt, her ex-boyfriend with whom she had moved to California, or at least, his double here in this reality. He looked the same, well over six foot and ripped like a professional body-builder. But this Kurt kept his eyes lowered to the floor as he stood in front of the middle-aged shop clerk who was a good foot shorter than him.

"Boy, do you still have your old collar lyin' around, the one you outgrew?" Marci asked. She winked at Penny as she trailed a hand across Kurt's well-developed pecs. "This is the way I like my men. My boy here's built like a Greek god."

"I think I could find it, mistress," Kurt answered when Marci had finished speaking.

"Good. Go get it," she commanded, and Kurt turned silently and left to do her bidding. He returned in a moment with a thick circular piece of metal, and he handed it to her warily.

"This is an old model, but it'll do," Marci said cheerfully. Before either Penny or Sheldon could think of a reason to refuse, she had sauntered up to Sheldon and snapped the thing around his neck. The ends fused together seamlessly.

"There, all better!" Marci beamed. "Now I'm sure the two of you can find somethin' in here that's more attractive than what you've got on now," she said pointedly.

" _Da_ , of course," Penny murmured, still in that awful accent. She nudged Sheldon toward the back of the store, hoping to get a better look at that collar in the hopes of removing it.

"Just a minute, dearie! You _do_ want the remote, don't you?" Marci called out.

Penny exchanged a relieved glance with Sheldon before heading back to the front of the store. The clerk, believing Penny was a foreigner, carefully showed her how to use the silver bracelet to control the collar. Penny called on all her acting skills to keep her expression neutral as the woman explained the "call" and "home" buttons and the "punishment" dial. Penny also made sure to ask how to remove the collar, on the pretext of wanting to upgrade soon.

Penny made her way back to Sheldon to find him frowning at a pair of pants. They were black and made from a shimmery spandex-like material, but they would at least cover all of him from the waist down. In a whisper, she explained what she had learned. They quickly agreed that Sheldon had to keep the vile collar on until they could find a hotel or somewhere else to stay. He explained in a low voice that he had found a computer terminal in the back, behind the dressing rooms. If Penny would create a distraction by talking to the shopkeeper, he was fairly certain he could create an account so they could purchase their clothing. Penny almost laughed at the way his mouth turned down at the corners when he referred to the scraps of spandex as clothes.

Browsing the racks, Penny was hard-pressed to find something that wasn't completely sheer. Marci followed her around and kept commenting how Penny had a nice figure and she should show it off (except Marci was referring to her as Natasha, the only Russian woman's name that had come to Penny's mind). Penny's final selection was a hip-length negligee of midnight blue lace, which appeared almost opaque at a glance. She wouldn't have felt self-conscious wearing it if Sheldon, with his eagle-eyed attention to detail, hadn't been around. She figured by now she'd given him a good fifteen minutes to work his magic on the computer, so she raised her voice and called, "How's it going back there, uh... boy?"

After a pause, the curtains of the dressing room parted and Sheldon emerged, wearing the black pants. His eyes were firmly fastened on the floor, but that was probably not due to any false modesty, but because he didn't want to see her reaction to the clothing that fitted like a second skin. Penny couldn't help the blush that swept up across her face. The fabric caught the light like satin, and the effect was positively sinful. She leaned slightly to one side so she could see the view from the back, and then bit her lip. She really, really shouldn't find this so sexy, but then again, that was the whole point of these outfits, wasn't it? Sheldon lifted his head briefly and gave a shallow nod. For a moment, Penny couldn't even think what he meant by it until she remembered that was their signal that he had successfully set up their identities and finances.

A/N: This story is only rated M because of the next chapter. If you don't want to read it, you can just skip to chapter 4 without missing too much of the plot.


	3. Chapter 3

Sheldon tried hard not to glower or recoil as the saleswoman came bustling up to him, exclaiming over the fit of the skin-tight black pants. Marci commented that she thought it was a shame that Penny wished to cover up so much of him. Then the woman's gaze flitted up to Sheldon's collar, and she paled. She leaned closer and poked at a small display with one finger while Sheldon tried not to flinch.

"That can't be right," Marci muttered. "His bio-readings are way off. When's the last time you used him?" she asked Penny.

"What do you mean?" Penny asked, taken aback. Surely the woman wasn't suggesting...

"Sex, dearie, you know..." Marci made an explicit gesture with both hands which made Penny blush. She didn't dare sneak a look at Sheldon's face.

"No, no, he just... carries things, runs errands," Penny said in her atrocious accent.

The older woman went rigid with shock. "You know that's illegal. It's against the Pact," she hissed. "All males are either to be managed by a private owner or turned over to the state work camps. You know how aggressive they can be when they don't have a regular release of their hormones." She looked thoughtfully at Penny. "You know, I have a friend who likes the skinny ones. If you're not interested in him, maybe she would give you a good price for him."

"No, no… that ees not necessary," Penny gasped. "We were just waiting to get to zee hotel."

Marci crossed her arms and scowled. "You won't get two blocks with his collar lit up red like that, and you know it. I don't know what kind of game you're trying to play here, Natasha. I've been more than fair to you, so I'll give you two choices. You can either take him into the dressing room there and deal with it, or I'm calling the police."

" _Da_ , no problem," Penny lied as she grabbed Sheldon's hand and pulled him into the tiny room before he could protest.

Once inside with a dark curtain giving them a modicum of privacy, Penny begin searching around frantically. Sheldon watched her for a moment before asking her what she was doing.

"Looking for a weapon," she replied crossly. "Maybe we can just hit that evil woman over the head and run for it."

He was flattered that once again Penny was trying to protect him. The most amazing part was that she had nothing to gain by it and indeed, much to lose. "You are forgetting about Kurt's _doppelganger_. You're no match for him," he commented. "And I would pose even less of a threat."

She stopped tugging on the dressing room bench, which was firmly anchored to the wall and faced him. "I'm not giving up, sweetie, and I'm not losing you. You heard what she said about those work camps."

Sheldon watched her search the room, but it was already obvious to him that they couldn't fight or bluff their way out. "Are you familiar with the principle of Occam's Razor?" he asked quietly.

"Of course not," she snapped, annoyed at the interruption. Obviously, she hadn't given up on the idea of fighting their way out. Her movement was arrested by a hand on her upper arm. He saw her expression change, and she blanched when she stepped back and he didn't release his hold on her arm.

"Occam's Razor states that the simplest explanation or solution is often the best one." He took a deep breath, trying to calm the waves of uneasiness that roiled through him. "The simplest solution would be to do as she suggested."

Penny's eyes widened as she realized what he was saying. Her cheeks reddened and then drained of color. She shook her head vigorously. "There's gotta be another way."

"I have already considered all possible options. We would attract immediate unwanted attention if we attempted to leave through the back of the store, where the inventory is kept. Attempting to overpower Kurt would be a futile gesture. We could try to simply walk out, but Marci has already threatened to call the police. Furthermore, she also suggested that this cursed device—" He tugged at the collar, a futile gesture. "—would also alert anyone within visual range that something is wrong."

"Wait!" Penny cried. "I have an idea. Why didn't I think of this before? You're probably going to hate it, but... what if you just... you know? I can wait outside the dressing room."

He looked at her blankly. Penny blushed and found herself resorting to hand motions the way that the shop clerk had done.

"If by that crude gesture, you are suggesting masturbation, I have already considered that. Unfortunately, we can't be certain that this collar is not also designed to register the female partner's bio-readings as well. In fact, I would consider it to be highly probable, given the dominant role women have in this society. Otherwise, through well-timed self-stimulation, men could render themselves physically incapable of servicing their female owners on demand."

Penny buried her face in her hands and moaned. "This is crazy. I don't want to force you into something I know you don't want to do."

In spite of his intense nervousness, Sheldon knew there had only ever been one woman for whom he felt the slightest bit of sexual attraction, and it had never been Amy. He'd always been annoyed by the way Penny treated him like a preschooler. By this time, he also knew exactly how to get under her skin. With a few well-chosen words, he could get her to act without stopping to consider the consequences. "I thought you were a 'big ol' five'," he taunted. "Stop treating me as if I were a child."

Her head snapped up, and she glared at him. "Maybe I wouldn't treat you like a child if you'd stop acting like one," she snarled.

"I'm not the one who's getting all emotional over a simple biological function," he argued.  
Her nostrils flared—definitely a weak point there. It was probably related to her tendency to substitute sex for love. Despite his reluctance to get involved in his friend's personal lives, he had noticed that when Leonard had accused Penny of not being romantic, her response had been to have sex with him more frequently.

"Fine! I'll show you a big ol' five," she shot back. She launched herself at him with more energy than finesse. Sheldon lost his balance and toppled onto the bench behind him. He was acutely aware of every curve of her body as she pressed up against him. She wrapped her arms around his neck and kissed him. It was the most enticing, sensual experience of his life, and he shuddered involuntarily as she made a throaty purr against his lips. Just as suddenly, she pulled away. Mistaking his wide-eyed expression for one of panic, she swore under her breath.

Sheldon didn't want to hear her compare him to a child again. He had always admired her courage, her resourcefulness and her compassion. Over the past few months, his admiration had grown into something greater and much more confusing. All his confusion had coalesced into a blinding revelation when she kissed him. He wasn't yet able to put a name to it, but he wanted more from her than just friendship. He especially wanted her to stop treating him like a child or a robot, something that looked like a man but didn't act like one. And so he acted on impulse for the first time in his life. He grabbed her shoulders and pulled her down into another kiss.

After a startled second where Penny went rigid with surprise, she melted against him. He let her take the lead, and his hands delved deep into the silky weight of her hair as he opened his mouth to hers. He could barely maintain any coherent thought as she pressed her body fully against his length. In his last internal struggle, he chose to set aside his inhibition and fears. With hands that trembled only slightly, Sheldon undid the ties at her shoulders, and the lacy gown slid down to her waist. He groaned as she guided his hands to her soft, lush curves. Sheldon was glad she had taken the initiative, because his wits had fled the moment her breasts were bared. She wiggled down a little further, and he could feel his body respond.

"Touch me," she whispered as she began kissing his neck, her tongue rasping over the faintest hint of stubble. He began explore her body with long, sensitive fingers, finding the places that begged for his touch: the nape of her neck, the curve of a hip, the soft skin on the inside of her wrist. Guided by instinct, he kissed her wrist and then laved it with his tongue. She gasped and ground against his lap, feeling that he was already hard for her. The surge of lust hit him fast and hard. She was whimpering by the time his hot breath washed over one taut nipple. "Please," she begged, and he obliged, no longer finding it strange to mimic with mouth and tongue what his hands had been doing moments before. Penny's whimpers turned into loud cries as he sucked on first one rosy peak and then the other. Suddenly, she pushed him back with a wicked smile.

"Your turn," she said huskily. She ran a hand along his chest, tracing a path downward. She leaned forward and followed with light, teasing kisses down his chest and abdomen. He felt himself growing rock hard as she arched sinuously against him. Working her way lower, she finally touched him with a ghost of a caress. He let out the breath he hadn't realized he'd been holding in a ragged exhalation and whispered her name, two syllables filled with longing and need. She rid him of his confining clothes and gasped appreciatively as his impressive length sprang free. She stroked him eagerly and expertly until he had to grab her hand to get her to stop.

"I'm very close," he said in a low voice.

She straddled his lap and lowered herself until the tip of his cock teased at her slick folds. "Do you trust me?" she asked.

He swallowed hard and answered yes. She kissed him softly as she took his length inside of her, and a small involuntary moan escaped her. Fighting for control, his grip on her hips tightened until he was afraid he might leave bruises. "Please..." he begged, not knowing how to ask for what he needed. She rose up and he surged forward, and they were moving together. He whispered her name, interspersed with other epithets, as he thrust inside of her. He had barely finished saying her name for the third time when his orgasm roared through him like a tidal wave, leaving him floating blissfully in a haze of endorphins in its wake.

She rested against his chest for a moment, listening as his breathing slowed and his heartbeat returned to normal. Then she pulled away. It seemed to Sheldon that their bodies separated reluctantly, and her absence was like a physical pain.

"Your light's green. I guess we're good to go," she commented wryly, her lips compressing into a thin line.

Dazed, he couldn't remember what she meant until she touched the collar. Slowly, he nodded. "I suppose we're free to leave now."

Penny used her discarded shirt to clean up, and then handed it to him without comment. When he gave it back, she rolled it into a ball and stuffed it under the bench.

"All right. Let's get out of here," she said. As they exited the shop, Marci was waiting on another customer, but she squinted at Sheldon's collar and then gave Penny an approving wink. Penny must have drawn on all her long-unused acting skills to smile and wave casually as they left.

For once, Sheldon followed Penny docilely, needing no prompting to trail a few paces behind her. It seemed to take all his concentration not to trip over his own feet. He felt bonelessly limp and lightheaded. His mind was so full of the intensely erotic memories, made just moments ago, that he couldn't begin to process what it meant or how he felt about it.

In less than half an hour, they had found a modest hotel and checked in. Sheldon's first priority was to take a long, hot shower because that often helped to clarify his thoughts. But this time, it didn't help. He emerged from the bathroom, fully dressed in a set of double-layered tees and khakis that he had retrieved from his backpack. He looked down at himself, suddenly dissatisfied. It felt wrong somehow to be wearing the same clothes as before. He wasn't the same; something had fundamentally changed. He now realized at least one of the reasons why people made such a big deal about sex. It was more than just a biological function, more than coitus, as he had always called it. The act had affected him in a deeply personal and emotional way, and it would take time for him to understand and assimilate these changes.


	4. Chapter 4

Sheldon's normal reaction to a situation completely outside his realm of experience was to pretend it never happened. The vividly erotic memories that tormented him gave the lie to the pretense, but what else could he do? Over the past several months, the only constant in his life, the one person he could trust, was Penny. He desperately needed their friendship for his own sanity and for survival. Any deviation from their previous paradigm was unacceptable. That's what he kept trying to tell himself, but it wasn't working. Even as externally he carried on exactly as he had before, his mind kept replaying those moments. He was distracted, and that in turn made him fearful.

Sheldon was, in a word, terrified. He felt lost. Everything familiar had been taken from him… everything, that is, except Penny. She had been invaluable. If he were perfectly honest with himself, he'd probably be dead by now if it weren't for her. Circumstances had forced them into a kind of intimacy that he was still trying to process. Yet he couldn't keep those all-too-brief moments from the back room of the clothing store from replaying in his head whenever he looked at her. He thought he could feel the heat from her body radiating towards him from ten feet away. His fingers twitched involuntarily as he imagined touching her again. Even though he know it was foolishness, he wondered if she could ever possibly... like him the way she had liked Leonard. He was scared to act, to risk rejection, and so their easy camaraderie became edged with tension.

* * *

In the next three worlds, they spent five hours dodging police in a world where everyone spoke Mandarin and speaking English was apparently a crime, seven hours getting lost in an endless maze of subways and subterranean tunnels, and two days in an arid wasteland. In the desert, Penny had to admit that restocking their supplies on the female slave owners' world had been necessary, but she was still pissed off at Sheldon. He seemed to have taken the fact that they'd slept together and buried it in some completely logical part of his brain. Except for multiple wide-eyed glances at her, he was acting as if nothing had changed. For all her casual relationships and multiple one-night stands, she had never slept with someone and then tried to remain friends afterward. (As far as she was concerned, that thing with Raj never happened, especially when she'd been too drunk to remember any of it.) She hated the way Sheldon was completely ignoring what had happened between them. Every time she looked at him, her mind kept replaying images of his broad hands splayed across her body or sensation he awakened as he moved inside of her. She winced. Nothing was going to be the same between them again.

 _Well, what were you expecting?_ she asked herself. _Some huge dramatic shift in his behavior? For him to start acting like every other guy you've ever met, sneaking glances at your body and giving you those hot, heavy-lidded stares?_ When she thought about it that way, she realized that yes, that was exactly what she wanted. Despite the fact that they'd had sex, he showed no signs of lusting or pining after her. It stung her pride a little. Maybe it was because she couldn't stop thinking about it: his skin so pale she could see the faint blue tracery of veins underneath, the feel of his broad hands pulling her closer, the way her name was torn from his lips almost involuntarily at the peak of ecstasy.

They always had this strange connection, been willing to do things for each other that they would do for no one else. Now, she felt like she didn't even know who he was anymore. The Sheldon she knew now seemed like a poor copy of the person he had once been. He had stopped quoting "fun facts" shortly after the second parallel world, when he realized that all his knowledge was completely irrelevant in an alternate universe. Dire circumstances had forced him to overcome his germophobia. After all, it was hard for him to worry about whether food had been properly cooked when he hadn't eaten in days. Perhaps they had both changed. Sheldon had learned to rely strongly on Penny's grasp of social situations, and her keen hand-eye coordination and ability to skin game without passing out had kept them from starving. But Penny was mourning the loss of that easy friendship they once shared.

* * *

Their next jump landed them on a tropical beach on what appeared to be an island. Despite his objections, Penny stripped down to her undergarments and went swimming. He stayed under the shade of the trees that line the beach, torn between fear of sharks and riptides, and disgust at how he wanted to do nothing but drink in the sight of her scantily-clad curves. He settled for building a palm leaf shelter above the high watermark. When he had finished, he surveyed it critically. A lack of long sturdy branches had limited the size of his shelter so that it was barely big enough for two people. He cursed himself for a fool at the rush of heat that swept through him at that thought, and then he set about making a second shelter.

Late that night, sleeplessness and desperation drove him to measures he hadn't resorted to in years. He fought to stifle his cries as he stroked himself, imagining it was Penny who touched him. While it temporarily relieved his physical tension, it only increased his desire to hold her in his arms and tell her how much he needed her. Yet the next morning, he looked at her, and the words died in his throat. Better to remain friends as they always had been than risk alienating her with unwanted declarations of desire.

* * *

Their next jump brought them to another civilized place, at first glance not so different from their own California. But within moments of their arrival, they were prisoners. As they walked down the sidewalk, trying to blend in, a man with a baseball cap pulled low over his eyes had gotten out of a parked van and approached them.

"You wouldn't happen to know the time, would you?" he asked with a disarming smile.

As both Penny and Sheldon reflexively glanced down at their wrists for watches they no longer possessed, the stranger suddenly reached out and yanked Penny against his side. A small but deadly looking pistol appeared in his hand, pressed against her ribs. The side panel of the van slid open to reveal a dark-skinned, middle-aged man and a petite young woman with short brown hair, also pointing firearms at them. Sheldon shot Penny a panicked glance. She moved her head back and forth in a barely perceptible negative.

"Just do what we say, and no one will get hurt," the man holding Penny said.

It was clear they had no choice. They were bundled into the van and handcuffed by the older man whose brown eyes creased into sympathetic apology as he did so. Lying back to back with Penny on the floor of the van, Sheldon reached out and brushed his fingers against hers, and she answered in kind.

After a ride which seemed interminably long and which probably lasted about half an hour, the van slowed and then stopped. Penny and Sheldon were led out into a large windowless room with key-card access panels on the doors. The older man guarded them while the young woman secured the garage door behind them. The younger man, obviously the leader of the group, rifled through their backpacks. Sheldon and Penny tensed as he held up their trans-dimensional device.

"Now, for some answers," the leader said grimly. "Who are you, and what are you doing with my prototype?"

After a moment of stunned silence, Sheldon couldn't help himself. " _Your_ prototype?" he burst out disdainfully. "That device was invented by the late Quinn Mallory, an extremely promising physicist, and it now belongs to me since I purchased it from his mother's estate sale."

Sheldon's words had an unexpected effect on the leader. At first, he seemed amused by Sheldon's speech, but at the phrase "estate sale", he paled and stumbled, reaching out a hand for support. The young woman reached him first, murmuring words of comfort as she and the other man helped him to a chair.

"It can't be true. She wasn't that old. My mom can't be dead," he said dazedly.

"They're probably just making it up, Mallory. I mean, who knows why they're really here," she said.

"That's right, Q-ball, but we'll make 'em talk," the older man said with a scowl directed at Penny and Sheldon.

The petite brunette got up and stormed over to them. "I'm Wade Welles. This is Rembrandt Brown and Mallory, but you already know who he is, don't you? Whatever the Kromaggs have promised you, it can't be worth betraying your own kind. Besides, now that you know who we are, what makes you think we'll let you leave here alive?"

The captives exchanged baffled looks. "I don't know what the hell a crow-whatsit is," Penny scowled, straining against her bonds. "But threaten my Moon Pie again, you skinny bitch, and we'll find out who's the real junior rodeo champ."

Sheldon frowned thoughtfully as he glanced back and forth between Wade and Mallory. "I believe this may be a case of mistaken identity. Penny, desist threatening that young woman, as I am certain you are frightening her." He continued, raising his voice. "Mallory… are you any relation to Quinn Mallory, the physicist?"

"I _am_ Quinn Mallory," the man replied, coming toward Sheldon with an intense expression on his face.

"Now that is a bold-faced lie," Sheldon snapped with surprisingly bravado for someone handcuffed to a chair. "I've seen pictures of the _late_ Quinn Mallory. You, sir, are an imposter."

"Not an imposter," replied Mallory, "but it's a long story. Let's just say I look a little different now. So if you aren't here to turn us into the Kromaggs for the price on our heads, what are you doing here?"

Sheldon and Penny exchanged glances again, and both started speaking at once. Their voices grew louder as each vied to make themselves heard.

"Whoa, whoa, hold your horses! One at a time!" Remy cried, grimacing. The pistol in his hands commanded their attention. "You first," he said when it was quiet, pointing at Penny.

"It all started when Sheldon brought home this box of old computer junk from a yard sale and started messing with it, "she said, shooting an annoyed look at Sheldon.

"Messing with it?" Sheldon cried, offended. "It was a relaxing project for my free time on the weekends. I sometimes enjoy dabbling in the lesser field of experimental physics," he explained haughtily. "I had just successfully reactivated one of the devices when Penny barged in from across the hall, probably looking to steal milk or engage in another poor life choice by having coitus with my roommate Leonard..."

"Oh, like hell I was!" Penny interrupted angrily.

By this point, Mallory was trying to hide a smile behind his hand, Wade was staring at them wide-eyed, and Remy's head swung back and forth between Penny and Sheldon like he was watching a tennis match.

"You're the one who got us stuck in this mess in the first place!" Penny yelled.

"Well, you're the one who just had to touch the interdimensional portal!" Sheldon cried.

"Then why didn't you just let it suck me in if I'm so useless? You think I ruined your perfectly organized, pathetic life! You'd be better off without me—isn't that what you think?" Although Penny was still shouting, tears were beginning to well up in her eyes.

"I don't think that..." Sheldon began.

"Admit it, you hate me, "Penny said with a sob as she began crying in earnest. The three captors exchanged uneasy looks.

"Penny, I don't hate you," Sheldon said, but seemed at a loss to know how to continue.

"Let them go, Remy," Mallory ordered suddenly in a gruff voice. "I recognize this device now. It was one of my earlier prototypes. I couldn't get the power conversion right, so I scrapped the design and started over from scratch. This guy must have fixed it. I guess they really were just in the wrong place at the wrong time."

Remy quickly unlocked their handcuffs while Wade, all sympathy now, offered Penny a tissue. She took Penny aside and the two women disappeared through a door. Sheldon stared after them in obvious discomfort.


	5. Chapter 5

Mallory watched Sheldon's face twitch uneasily as Wade led a weeping Penny away. "Don't worry. I'm sure if you just apologize, everything'll be fine," he told Sheldon, clapping him on the upper arm.

Sheldon pulled away and glared at the other scientist. "I have nothing to apologize for."

"Man, you suck at this relationship stuff," Remy chided, shaking his head. "You gotta show her you're sorry, maybe squeeze out a tear or two, and then she'll forgive you."

"You are mistaken. Penny and I are merely friends; we're not in a relationship," Sheldon said stiffly.

Remy groaned. "Here we go again. What is wrong with you scientist types? Why do you have to wait till it's too late to tell a woman how you feel?"

"I... I don't..." stammered Sheldon, for once at a loss for words. He could no longer claim that he had no feelings for Penny, but the true nature of his feelings was still a mystery to him. Of one thing he was absolutely certain: far from being useless as she had said, Penny was the most important person in his life. When she had first seen the portal and reached out to touch it, he had lunged for her in a panic. His only thought had been that he couldn't let any harm befall her. Yet it had. He had stranded her far from home, relied on her to save him time and again, and never even thanked her.

"That's what I did," Mallory said, breaking Sheldon's reverie. "Back when I was just Quinn, before all this sliding began, Wade and I were best friends. But then somehow she fell in love with me, and I didn't know how to handle it. I kept ignoring the issue, thinking I'd have time to deal with it later, but I never got the chance. Wade was separated from our group a few years ago and captured by the Kromaggs. I meant to go back and save her, but..." Mallory's voice broke, and he turned away abruptly.

"I don't understand. She seems fine now," Sheldon said in bewilderment.

"Yeah, this sliding gets confusing. That's what we call traveling between parallel worlds: sliding," Remy said. "You see, the Wade who grew up with Quinn sacrificed her life to save ours. This is a different Wade, like her twin. We met the Wade who's with us now on a world similar to our earth. She never knew Quinn on her world, but the moment she met him, it was like... like she met her destiny. She left her whole world behind to follow him."

"I knew I'd been given a second chance that I didn't deserve," Mallory said, taking up the story again. "I promised myself I'd spend the rest of my life trying to make it up to her, to love her the same way that she loved me. Don't make the same mistake I did. Sliding's dangerous, and you never know how much time you have together."

Sheldon swallowed hard. "I'm not very comfortable with feelings, either mine or someone else's. I have spent my entire life trying to avoid the unnecessary complications of emotional entanglements."

Remy sighed and pulled out two stools from under a lab bench. "Have a seat, my man. The love doctor is in. Tell me all about you and this girl Penny."

* * *

In a decrepit but still-functional bathroom, Penny blotted her eyes with a damp paper towel that Wade handed to her. "Thanks. I don't know what's the matter with me. I guess I've just been under a lot of stress lately."

"Sounds like you and this guy Sheldon had a fight. Men can be so clueless," Wade said sympathetically.

Penny grimaced. "I wish it was that simple. No, we fight all the time. This is different. The problem is, we're friends who sort of became... friends with benefits."

"What are friends with...?" Wade began to ask, and then exclaimed "Oh-h-h!" as she grasped Penny's meaning from the suggestive smirk on the blonde's face. Blushing a little, Wade asked, "So you and Sheldon became lovers, but now you've figured out you have feelings for him?"

Penny stared at Wade for a moment before started laughing. "Me... in love with Sheldon? Nuh-uh. No way."

"I never said anything about love," Wade replied with a discerning look.

"Oh... well... I... You don't understand," Penny protested weakly. "This is Dr. Sheldon Cooper, PhD, we're talking about. I mean, he's batcrap crazy. His whole life runs on a schedule, and he's so brilliant he makes me look like a blonde monkey, and he hates being touched..." She drew in a long, shuddering breath. "Except all of that's changed, everything but for the part about him being a genius."

"So why is that an issue?" Wade asked. "Quinn is a genius too. All that means is that he doesn't need me to be one as well. In fact, he gets too wrapped up thinking about science and strategy. He needs me to keep him grounded, to keep him connected to the rest of the world and to take care of him. Sure, it would be nice if I had a clue what he was talking about when he goes on and on about one of his theories. But I don't need to understand in order to support him and believe in him. That's more important than us connecting on an intellectual level."

Penny frowned thoughtfully. "Before this all started, Sheldon had a girlfriend, Amy. She's brilliant too—she's got a doctorate in neuropsychology or something like that. Sheldon liked that he could talk about his work with her, but he didn't really treat her like a girlfriend. They had this weird relationship contract, and the most they ever did was hold hands. They used to really tick each other off fighting about whose science was better, or whose work mattered more."

"That's exactly what I mean," said Wade. "Seems to me like they would have both been happier as friends. Why did they stay together if Sheldon had no interest in her romantically?"

Penny grimaced. "I dated Sheldon's roommate and best friend for a while. We broke it off, but then later, I agreed to a beta test… a second chance. I think that's when Sheldon begin to realize that Leonard wouldn't always be around. Even though he would never admit it, I think he didn't want to be alone. So I think he asked Amy to be his girlfriend because it seemed like a perfectly logical solution to him, a 'relationship of the mind', he used to call it."

"Sounds like Sheldon has a hard time coming to grips with his feelings," Wade commented. "Is it possible that's why he's been so stand-offish?"

"I hadn't thought of it that way, but yeah, I guess it is," Penny admitted.

"You need to talk to him," Wade urged. "The two of you have such a strong connection. I feel like you belong together on a very deep and profound level. I think your fates are intertwined."

Penny looked at the petite brunette in surprise. There was empathy in her voice and a kind of wisdom that Penny hadn't heard in a long time. Despite Sheldon's rigid disapproval of anything that could be proved scientifically, she believed in things like fate and destiny. Meeting another young woman who was similar to her in so many respects made Penny feel like she had found a friend. The fact that her new friend had somehow managed to forge a relationship with a brilliant and temperamental genius was intriguing.

"I get the same feeling about you and Mallory. How did the two of you meet?" Penny asked curiously.

"That's another long story," Wade said with a smile. "But if Quinn and your guy Sheldon start talking about physics, we might have all day."

When Wade and Penny finally rejoined the group, they found the men in a small knot, heads together. Sheldon and Quinn seemed to be arguing about physics, while Remy kept trying to turn the conversation back to some kind of guerilla warfare tactics.

Wade rolled her eyes. "What did I tell you? Quinn has finally found someone who can understand his theories. They could be at it for hours... maybe even days."

"In that case, do you have a place I can get a shower?" Penny asked, holding up a limp strand of hair.

"Oh, of course, where are my manners?" Wade said with a smile. "Come on. We have a living area back here. Let's get you settled in. It looks like you'll be staying a while."

* * *

Penny and Sheldon had eight days until their next jump, but their new friends were planning on staying on this world for a few weeks. At first, the original group of sliders had been constrained by the limits of Quinn's device, which would tell them when the next portal would occur. However, on their first slide, they had been forced to use the device to open a portal off schedule. The result was that they had also gotten lost, unable to return to their own dimension, which they called Earth Prime.

They spent a few years trying to find their way back home, but then they learned that they weren't the only sliders. A race of aliens known as the Kromaggs used the same technology to conquer other dimensions and harvest whatever resources they wanted. Penny and Sheldon were surprised to learn that there was a human who was doing essentially the same thing, a man named General Rickman. The sliders also considered him an enemy. Although wary of him, they had abandoned their search for him after the death of Maggie, an ally from Rickman's world who wanted revenge on him. After she was killed, Wade and Remy prevented Mallory from going off on a vendetta. They rightly considered the Kromaggs to be the greater threat.

The sliders' next goal was to find a way to identify the different worlds they visited, creating a map of sorts. After that, they needed to find a way to control the slide so they could choose their destination. Over the next few days, Sheldon and Mallory worked feverishly to come up with a solution to the first problem.

"You know, we could really use your help on a more permanent basis," Mallory suggested as he and Sheldon wolfed down cold food while scrutinizing their work.

"What are you suggesting?" Sheldon asked.

"You know what I'm saying. Come with us. Help us. I freely admit your general knowledge of physics is superior to mine, not to mention twenty years more current. There's a lot of worlds out there that need our help. You could be their hero."

"An unsung hero, no doubt, since the denizens of those worlds must remain ignorant of this sliding, as you call it," Sheldon retorted.

"What, is that all you care about? Fame, recognition?" Mallory scoffed.

"No, that is _not_ all I care about," Sheldon retorted angrily. "But with the exception of Penny, everything else that matters to me is back on _my_ earth. I would be a fool to give that up for vague promises of glory and the supposed betterment of humanity."

Mallory pressed his lips together and narrowed his eyes at Sheldon. "I see I was mistaken about you," he said tightly. He turned back to their calculations without another word.

Sheldon didn't know that at the same time, Wade and Remy were trying to convince Penny to stay with them. Wade especially liked that Penny was tough and a crack shot. Wade was a gentle soul who would rather die than actually shoot someone. Whenever she brandished a weapon, it was just for show. She knew her pacifist ideals gave Mallory nightmares. The two of them both longed for an end to the war so they could settle down quietly somewhere, but there was no guarantee that would ever happen. With Sheldon and Penny's help, Wade hoped to even the odds.


	6. Chapter 6

Sheldon threw himself into the enormous task of trying to solve the puzzle that Quinn—or rather, Mallory—had been working on for years. Penny had little to do except hang out with Wade and Remy. Now that they were no longer her captors, she found she liked both of them immensely. Wade was sweet and kind, but also fiercely loyal to Mallory. Remy had a great sense of humor, which had never dimmed no matter how bleak the future appeared. Wade had especially missed female companionship, and she took every opportunity to try to convince Penny to travel with them. Her eager guilelessness reminded Penny a little of Amy when they had first met.

While Penny didn't feel any particular obligation to these people, Wade's arguments began to work on her in a different way. She and Sheldon had been so focused on getting home that she had never considered the ramifications of going back. Now as she pondered everything that had changed, she started to dread the idea of going home. As a dimension-traveling slider, she was a strong, capable survivor with an impressive set of useful skills. In her version of Pasadena, she was nothing more than a penniless waitress who drank too much and blew most of her money on shoes. Worse, if she went back, she would have to face Amy, knowing she had stolen something precious that Amy considered hers: Sheldon's innocence. Then there was Leonard, whom she had technically cheated on, no matter that at the time she never thought she would see him again, or that she believed her actions had saved Sheldon from a fate worse than death. She also knew she couldn't ask Sheldon to keep what happened between them a secret. Not only was he pathologically incapable of doing so, but it wasn't fair to him either.

Perhaps she turned to Wade and Remy out of desperation, but she made a good choice in doing so. Neither of them were inclined to be judgmental, and so Penny found herself telling them all about her former life in her Pasadena. The funny thing was that the more Penny talked about her job, her friends and the decisions she'd made, the more defensive she got. So Amy and Bernie made fun of her lack of education—weren't friends allowed to joke around? And so what if Leonard never really believed she had what it took to be an actress—nobody's perfect, right? And whose business was it anyway if she liked to drink and dance and buy shoes that cost more than a month's rent just to feel better about her miserable life?

The moment those last words were out of her mouth, she actually heard what she had been saying. She _had_ been miserable, and she suddenly couldn't think why she had been trying to defend any part of her old life. Her jaw dropped, and her face suffused with color. Under the sympathetic gazes of her new friends, Penny suddenly started sobbing. It was the kind of helpless, raw crying that she hadn't experienced since high school. Remy exchanged startled glances with Wade, then indicated with a nod of his head that he would give the two women privacy. He may have once had a hit single titled "Cryin' Man", but that didn't mean he was comfortable trying to console a woman he'd only known for a few days.

Wade scooted closer to Penny and put an arm around her shoulders while producing a tissue from her pocket. When Penny's sobs finally subsided, Wade gamely asked her if she wanted to talk about it. Blonde curls shielded Penny's face as she began to speak in a low voice.

"I just started listening to myself... all the excuses I was making for the way my friends behaved, or for the fact that Leonard and I never talked about anything important and always brought out the worst in each other. And then I thought, I'm no better. I've been wasting the last several years of my life drinking while sponging off my friends because that was easier than chasing my dreams. To be honest, I think it's too late for me anyhow. If I had worked really hard when I first came to California, maybe I could have made it as an actress. Now, I'll never know, because I never really tried. And that's the thing that's killing me. All this time, I've wanted to get back to my Earth so badly, only now I realize I don't want to be the girl who fits into that life anymore."

She fell silent, and Wade asked quietly, "So what do you want?"

"I don't know," Penny said slowly. "I still want to do something important, you know? Something that people will remember me for." She looked over at Wade and reddened. "I guess that sounds pretty stupid when I say it out loud."

"I can't think of anything better than to make your life count for something," Wade said quietly. "That's why I'm here. When I met Mallory, I knew he was going to do great things. I could either choose to go along for the ride, or spend the rest of my life wondering what I'd missed out on. I'm not very brave. I'm not even much of a fighter. But I chose this life because I had to know who I _could_ be if I took a chance."

Penny nodded. "I know exactly how you feel. I once ordered this pair of Louboutins—they're the most amazing shoes and so freakin' expensive—but they fit like a size seven, even though the person I bought them from on eBay swore they were a seven and a half..." She broke off, seeing the look of bewilderment on Wade's face. "What I mean is, it didn't matter how great everyone else thought the shoes were, because they didn't fit me. Going back to my Pasadena would be as painful as going clubbing in shoes a half size too small."

"So what are you going to do?" Wade asked breathlessly.

"I think... I think I'm going to stay with you and Remy and Mallory," Penny said.

Wade squealed and hugged her.

"This is a huge decision. Can you promise not to say anything to anyone else until I'm completely sure?" Penny begged.

"Of course," Wade replied solemnly, but her eyes were dancing with excitement.

* * *

Penny spent the next few nights tossing and turning sleeplessly while she mulled it all over in her head. Finally, she was sure. She had to make a decision that allowed her to be able to face herself in the mirror each morning, and that decision was to not return home.

She told Sheldon the next morning. He and Mallory had been working feverishly. While it may have seemed unfair for her to dump this on him, she knew him well enough to know that he needed time to process it. Of course, he tried to argue with her. She simply walked away, saying he wasn't going to change her mind. Mallory watched Sheldon with wide eyes. At this point, he had grown to respect the temperamental physicist enough that he didn't know which outcome he desired: for Sheldon to be able to return to his own reality, or for him to stay and help them.

For Sheldon, this was nothing short of a nightmare. If he were perfectly honest with himself, he had imagined that he would return home to his apartment, his friends, his comic books and his work like nothing untoward had ever happened. Obviously, that couldn't happen if he left Penny behind. As he thought about returning to his former life, something strange happened. His pleasant memories of his routines seemed to dim and recede. He couldn't understand why he should be so affected by Penny's announcement, but clearly he was.

"Hey, Coop, you okay?" Mallory said, interrupting his train of thought.

"No, I am not okay, and I told you not to call me that," Sheldon snapped.

Mallory backed off, hands held up in a gesture of surrender.

Sheldon turned back to his calculations, retreating into the comforting predictability of physics and mathematical formulas. Two days later, it was time for him to leave. He had been so busy working with Mallory, checking and rechecking their work, that he hadn't had a chance to talk to Penny. At least, that was what he told himself. The truth was that he didn't know what he would say to her. The look of anguish on her face as she told him why she was staying had burned itself into his mind. Even now, as he approached her, he barely knew where to begin.

"Are you all packed?" she asked, trying for a smile but failing.

"I have everything I need," he said. As he spoke, it was as if something broke loose in his psyche. It was true. He was no longer the same person. He didn't know if the new person he was could fit back into his old life, with its exacting patterns, the germophobia which now seemed ridiculous, the expectations of his friends that he was not only crazy but an asexual prude as well. He saw it clearly now. He could go back, let his new abilities fade away, and shrivel back into the old shell of his existence. Or he could rely on every ounce of courage he possessed to embrace a new future.

"Do you know why Batman is one of my favorite superheroes?" Sheldon asked. The expression on his face was strained and intense.

Penny's face showed her surprise at the _non sequitur_. "Uh… I guess I always thought it was all his cool gadgets," Penny said gamely, wondering where he was going with this.

"Bruce Wayne became Batman by his intelligence, determination and hard work... and, of course, he also had a vast fortune. When I was younger, I thought that maybe I could become like him. I dreamed of being a hero, someone whose brave deeds inspired admiration. Once I started going to school, I became convinced that people were by nature cruel, selfish and not worth any such effort. It wasn't until I met you that I began to care about people again, and the person I care for most is you. If I go back now, I'll be back among my friends, in my familiar routine with the life I've arranged exactly as I wanted it. The only thing I would be giving up is you."

He watched her carefully, saw the tightness in her face and the blank look of defeat in her eyes. Slowly, he slid the straps of the backpack off his shoulders. It dropped to the floor with a loud thud. She looked up at him, uncomprehending.

"I can't do it. I can't give you up. So I'm giving everything else up instead. I'm staying because... I love you, Penny."

She shook her head. "No. No, Sheldon, you don't know what you're saying. You have to go. I know how much you hate this jumping around between dimensions. If you don't go, you're going to regret it, and I won't be responsible for that."

He took a few steps closer until he had closed the distance between them. "If I leave you, I would regret it for the rest of my days. And I choose to be responsible for my own decisions," he said, cradling her face in his hands. She met him halfway when he bent down to kiss her, and the tears rolled down her cheeks as she held onto him tightly. Behind them, a swirling vortex appeared unnoticed. After a few moments, it vanished again. Sheldon and Penny were oblivious to everything but each other.


	7. Chapter 7

_Eighteen years later..._

A swirling vortex of blue energy, accompanied by flashes of static electricity, appeared in the sky. Six people tumbled out. A woman with long blonde hair pulled back in a ponytail sat up and rubbed her backside ruefully.

"Why is it that with all the advances in technology we've made, we still get bruises on every landing?" Penny complained.

Lee, her oldest, reached out a hand to help his mother, but Sheldon beat him to it. "Perhaps it's so I can kiss them better when we're alone?" he suggested with a twinkle in his eyes.

"Eeew..." "Gross!" This was from two identical sandy-haired boys who were already exploring their surroundings.

"If you guys start kissing again, I'm outta here!" one of them exclaimed.

"Ryan, Brandt, you know the rules. We stick together," Sheldon admonished, even though he hadn't taken his eyes from Penny.

She accepted his help and did kiss him briefly before turning to their daughter. "Put that away, Mel. I said you wouldn't need it here."

The teenaged girl, tossing magenta and lime colored locks of hair out of her face, pouted as she slid her favorite throwing knife back into its sheath in her boot.

"I can't believe you and Dad grew up on such a soft world," she muttered.

"Well, we did, and so did everyone you're going to meet here, so be nice," Penny scolded. She caught sight of her oldest son stuffing his Glock into a backpack and nodded approvingly.

"When do we get to meet Uncle Leonard?" asked Ryan excitedly.

Over the heads of the twins, Penny and Sheldon exchanged a look fraught with meaning. Sheldon came over to her and put an arm around her waist.

"Your dad and I have decided that we're going to go see him first… alone," Penny told them.

* * *

In another part of the city, a thickset man with graying curls set aside a stack of papers he was grading and got up from his couch with a wince. His left knee was acting up again. He couldn't remember if he had injured it testing the anti-grav hover skates that he and Howard had invented (they had been a disastrous failure), or if that was where his ex-girlfriend Kayla's bratty kid had kicked him. Regardless of how he had hurt himself, he had been left with a permanent twinge that caused his whole leg to stiffen if he sat in one position for too long.

There was a knock at the door and Leonard looked up, bemused. He hadn't been expecting anyone.

"I swear to God, if another grad student has tracked me down to prank me..." he muttered irritably as he limped toward the door.

He looked through the peephole and froze, not trusting his eyes. It looked like... no, it couldn't be... but it looked just like...

"Penny," he breathed and flung the door open.

She smiled when she saw him, and the warmth of her expression and the glow in her green eyes catapulted him back to the day they had first met. He had fallen hard and fast for the beautiful blonde next door. They had dated for a while in an on-again, off-again relationship. He had never lost hope that someday she would be his forever, until she disappeared along with his crazy roommate. He had searched for years. Howard, Raj, Bernadette, Amy, Penny and Sheldon's families... all of them had spent years tracking down any lead, any mention of a tall, annoying physicist or a young wanna-be actress turned waitress. But as their leads dried up, it was harder to cling to the hope that Penny and Sheldon might be alive. As the years passed, eventually they all stopped believing they would ever see their loved ones again. Only Raj and Mary Cooper persisted, each possessed of a strong feeling that Penny and Sheldon were still alive and out there somewhere.

Although he hadn't been dating Penny for very long before she disappeared, Leonard still mourned her as the lost love of his life. He'd had a brief, secretive affair with Amy as they bonded over their mutual loss, but that relationship had been short-lived. Later, he found that he could get a lot of sympathy from a certain type of girl by telling his tragic tale, combined with his signature head-tilt and sad puppy-dog eyes. He'd gotten married in his mid-thirties, and he and Karen had stayed together for six years. They'd never had children, one of the major rifts in their relationship. Now, as Leonard stood gazing upon a ghost from his past miraculously brought to life again, he wondered if fate had conspired to give him a second chance with his first love.

"Hello, Leonard," Penny said softly, breaking him out of his stunned silence.

"Penny... is it really you?" he asked stupidly.

"It's really me. It's so good to see you again," she said, smiling and hugging him. Leonard was elated. This was everything he had ever dreamed of.

 _A-hem!_ Leonard's jaw dropped as he glanced up to see his old roommate standing next to Penny, looking less than entirely pleased.

"Sheldon! Hey buddy, I didn't see you there!" Leonard cried, secretly cursing his luck for a second even as he looked over his friend in amazement. "I… whoa, what happened to you?" he blurted out as Sheldon stepped forward and the light illuminated a mass of scar tissue that distorted the left half of his face.

"It's a long story. You see, fifteen years ago while I was leading a counterintelligence operation..."

Penny groaned loudly and smacked her forehead with an open hand. "Honey, every time you tell this story, it gets longer and longer. Can't you just say 'plasma grenade' in a macho voice and let everyone's imagination fill in the details?"

"I don't see the fun in that," Sheldon pouted.

Much to Leonard's surprise, Penny only laughed delightedly and looped her arm through the crook of Sheldon's elbow. "We have a long story to tell. Can we come in?"

Leonard hadn't missed the way Penny was hanging on Sheldon's arm, or the fact that Sheldon hadn't even flinched when Penny touched him. A sneaking suspicion began to work its way to the forefront of his mind, but he quelled it fiercely. _Sheldon and Penny together? Ridiculous!_ Why, in all the time he had known Sheldon, he had never shown the slightest interest in any girl. Even his former roommate's nominal relationship with Amy had been nothing more than a relationship of the mind. He knew that for sure because he had been Amy's first lover. She had yielded to him on the night she had finally given Sheldon up for dead.

Leonard shook his head as if to clear away his thoughts as he led them into his living room.

"Wow, a leather sofa... this brings back so many memories!" Penny exclaimed delightedly as she sat down. "Tell me you still keep in touch with everyone: Howard and Bernadette, Raj, Amy..." she pleaded.

"Yeah, we sort of all went our separate ways over the years, but we still vid-chat each other and get together from time to time," Leonard replied. "But enough about them... where have you two been all these years? What happened to you?"

"You have to understand that there are going to be some things we can't tell you," Sheldon said gravely.

"I _knew_ it!" Leonard breathed, trying not to stare at the livid scar on Sheldon's face. "What is it? Secret government project? Time travel? Aliens?"

"No, not exactly, and yes," Penny put in with a grin.

"Penny, please, there is a proper order to things, and you are not adhering to the linear sequence of events," Sheldon complained.

A look passed between the two, and Penny leaned in close to Sheldon and murmured in his ear, "I'll give you linear sequencing, all right."

The suspicion came roaring back in Leonard's mind as he saw the very non-robotic, non-asexual way his former friend was looking at the woman of his dreams. ( _Oh, it's_ former _friend now, is it?_ A corner of his mind mocked.)

"Our tale begins eighteen years ago on the eve of the fifteenth of November..." Sheldon began, redirecting attention back to himself.

Penny rolled her eyes but didn't interrupt again. Leonard listened in astonishment as Sheldon described how he had purchased the box of components that had once belonged to Quinn Mallory, and then reassembled one of the prototypes. Penny had shown up for laundry night and accidentally touched the portal. Sheldon had reached for her, and they had both been pulled inside. It was only by the greatest of coincidences that Sheldon had been holding the prototype in his hand. They discovered that the device opened a door of sorts between alternate universes, places that could be very similar or vastly different from the Earth they knew. It wasn't long before they met the sliders.

"What are the sliders? Are they the aliens?" Leonard asked eagerly.

"No, they're our friends... even if they did start out by kidnapping us," Penny added with a grin.

"The sliders were a small group of fellow dimensional travelers whom we met almost a year after we left our Earth Prime. They had already encountered the Kromaggs, a hostile alien species which subsisted by pillaging resources from more vulnerable worlds. They persuaded Penny to stay and help them, and that was when I discovered that Penny meant more to me than all my comfortable familiarity I thought I had been missing."

Leonard gaped at them, incredulous. "Wait, you and Penny were together?"

"We've been married sixteen years..." Penny began.

"It's fourteen years; how many times do I have to tell you that a cetacean mating ceremony does _not_ count as a wedding?" Sheldon interrupted.

"Only a few hundred more times," Penny said with a laugh. It had the feel of an old argument. "I thought the cetaceanoids were such a romantic people."

"They weren't human; it doesn't count," Sheldon retorted, but the corner of his mouth on the unscarred side of his face was now lifting in a smirk.

"So you're married... I mean the two of you... to each other?" Leonard stammered.

"Yup," Penny said, just like she used to do. She turned her hand palm up and displayed a series of tiny symbols, tattooed on the inside of her wrist. To Leonard's amazement, Sheldon did as well, disclosing a set of identical tattoos. "You only have to get a ring caught in the magazine of a laser rifle once to make sure you never make that mistake again," Penny said wryly. "We still have our rings in a box somewhere, but we don't really need them."

Just then, Sheldon turned his head toward the door, as if in response to some noise that only he could hear. "I'm afraid the natives are getting restless," he murmured to Penny.

She grimaced. "Might as well get it all over with at once. The thing is, Leonard, our kids grew up hearing stories of our old life on Earth Prime. When they heard we were coming back here, they couldn't wait to meet you, especially the twins. I hate to dump this on you all of a sudden, but is it okay if they come in? We told them to wait outside."

Leonard gaped at them for a moment. "You… you have children?" he finally managed to stammer.

"Yes, four of them, although sometimes I have a hard time comprehending it myself," Sheldon said. "Our firstborn was named after me, although we've always called him Lee. He's seventeen and has inherited many of my finest traits," he announced proudly.

"Then we had a daughter," Penny said. "We named her Melissa after Sheldon's sister, but we call her Mel. She's kind of going through a rebellious teen phase right now, but she's equally talented with computer systems and throwing knives."

"Mel is fourteen now. We didn't plan on having more than two children, but someone forgot to take her birth control supplements," Sheldon said sternly while his eyes twinkled at Penny.

Penny smirked at him. "I knew you wouldn't mind having a few more children when they're all as smart as you."

"You mean as brave and resourceful as their mother," Sheldon corrected as he leaned in to kiss his wife for far longer than Leonard was comfortable with. Leonard quickly jumped up and went to open his front door, just to give himself something else to do besides watch his old roommate gaze lovingly at his ex-girlfriend. Two young boys practically burst into the room as soon as he opened the door.

Penny pulled away from her husband. "And now you've met our twins, Ryan and Rembrandt."

A teenaged girl leaning against the wall opposite the doorway, arms crossed over her chest. She looked Leonard up and down in a sneering manner that could only be described as insulting. The dismissive huff she made was downright offensive. Leonard stared at her. Except for her hair, dark with neon streaks, she was the spitting image of Penny.

A lanky figure moved in front of her protectively. "Knock it off, Mel," he said, sounding annoyed, but there was something about his stance that made Leonard feel a little nervous. The young man's penetrating gaze swept around the room before he looked back at his sister and gave her a subtle nod.

"I'm Lee. It's a pleasure to make your acquaintance," he said, holding out a hand to Leonard, who shook it but looked dazed. Mel, meanwhile, had flowed past them and was examining the apartment with a critical eye.

"Wow, look at all the cool stuff!" one of the younger boys yelled. Leonard swung back to see Sheldon snatch his replica of the bottle city of Kandor away from the child's outstretched hands. Sheldon brushed off the top of the glass dome, dislodging a fine shower of dust.

"Actually, this one used to be mine," he said with a smile. "I collected things like this too, a long time ago. It was one of the things your Uncle Leonard and I had in common, and how we became best friends." He glanced at Leonard. "I'm glad you kept it."

After half an hour's visit, Leonard was strongly reminded why he didn't like kids. He had always thought he wanted some of his own, but only in that vague fantasy sort of way where they would adore him and do everything he said. The Cooper brood, while being fairly well-behaved, were still nerve-wracking to be around. The twins were practically vibrating with curiosity as they had to touch and examine everything they saw, asking a million questions as they did so. Mel smirked insolently at him, and at one point, pulled out a wicked-looking hunting knife and starting throwing and catching it one-handed. Lee was quiet and self-contained, but his eyes seemed to miss nothing, and he was constantly scanning his surroundings as if on guard for any sign of trouble.

A faint chime sounded, and Leonard startled. Sheldon smiled apologetically as he retrieved a tiny, thumb-sized device from his pocket. "Excuse me, Leonard, but I'm afraid we're going to have to cut this visit short. Duty calls." Penny's eyes sparkled in anticipation as she rounded up their children. The kids moved toward the door, the twins more reluctantly since they wanted to play with all of "Uncle" Leonard's action figures.

"Wait… where are you going? You've been gone for twenty years; you can't just walk away again," Leonard protested.

Sheldon and Penny exchanged amused glances while Mel openly smirked at his display of insecurity.

"We'll be back, Leonard, I promise," Penny said. "Now that the war's over, we've been reassigned. Earth Prime is our home now, but that doesn't mean it's the only world out there." Penny smiled sympathetically at the baffled look on Leonard's face. "Don't worry; you'll get used to it."

"Ready, my love?" Sheldon asked, sliding an arm around her waist.

"Always," she grinned.

They left the apartment without a backwards glance. Leonard waved gamely as they disappeared around the corner. As he turned back to his apartment, there was a sound like a rushing wind and a bright flash of light. He froze in shock and then raced around the corner as fast as his bad knee would allow. The Coopers had vanished into the ether. There was a time when Leonard would have envied them. Now he just shook his head at the empty hallway and retreated back into his home. "Better them than me," he muttered as he shut the door.


End file.
